Attached Link: http://www.debevec.org/

I think some people have a misconception as to what HDRI really is, and what it's actually used for in 3D. The lightgen utility just extracts certain info from a light probe in HDRShop and translates that information to generate a standard lighting rig to basically "fake" HDRI, using standard lights, in apps that don't support HDRI probes natively. However, in some 3D apps, the light probes can be used directly, and no standard lights need to be added to the scene in order to use them. Light is calculated by advanced rendering engines using the information in the probe directly to illuminate a scene with a global high dynamic range of colors, which provides a much more realistic lighting model than using standard 3D light rigs. Check the link for more information on what HDRI actually is. It's the webpage of Paul Debevec, the founding father of HDRI.

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Tools :  3dsmax 2015, Daz Studio 4.6, PoserPro 2012, Blender v2.74

System: Pentium QuadCore i7, under Win 8, GeForce GTX 780 / 2GB GPU.